Fix our copy of the tarball packaging script

This commit fixes our copy of create_tarball_kf5.rb to work against Invent.

It now fetches the tarball from GitLab, and extracts the tree following the format of git-archive.

Additionally, I added a few defaults for the category (sysadmin namespaced the repos when moving them to Invent), tag (GitLab by default returns the master branch), and skipped any possible app names that are not defined in config.ini.

CCMAIL: kimageshop@kde.org

Test Plan

1. Go to packaging and run ruby ./create_tarball_kf5.rb -n -a krita.
2. Then wait for the script to finish.
3. Check that the contents of krita-4.3.0.tar.gz match or exceed the contents of https://download.kde.org/stable/krita/4.3.0/krita-4.3.0.tar.gz (my changes now pack dot-files, as supplied by GitLab).

Formalities Checklist

• I confirmed this builds.
• I confirmed Krita ran and the relevant functions work.
• I tested the relevant unit tests and can confirm they are not broken. (If not possible, don't hesitate to ask for help!)
• I made sure my commits build individually and have good descriptions as per KDE guidelines.
• I made sure my code conforms to the standards set in the HACKING file.
• I can confirm the code is licensed and attributed appropriately, and that unattributed code is mine, as per KDE Licensing Policy.